We describe a design for a two-pass recirculating 1.3 GHz superconducting linac as a driver for the suite of free-electron lasers proposed in the UK New Light Source project. The machine will deliver longitudinally compressed electron bunches with repetition rates of 1 kHz with an initial upgrade path to increase this to 1 MHz. A modular philosophy is employed to separate beam injection and
extraction from a three stage compression scheme. Results show that the necessary high peak currents can be achieved whilst preserving beam quality.